// 数组
const arr: (number | string)[] = [1, "2", 3];
const stringArr: string[] = ["a", "b", "c"];
const undefinedArr: undefined[] = [undefined, undefined];

// type alias 类型别名
type User = { name: string; age: number };

class Teacher {
  name: string;
  age: number;
}

const objectArr: Teacher[] = [new Teacher(), { name: "dell", age: 26 }];

// 元组 Tuple，数组的长度和类型都是固定的
const teacherInfo: [string, string, number] = ["Dell", "male", 18];
// csv
const teacherList: [string, string, number][] = [
  ["dell", "male", 19],
  ["sun", "female", 26],
  ["jeny", "female", 38],
];
